The present invention relates to a device for absorbing impacts between a mobile machine such as an automotive vehicle, an elevator, a train, a boat, a cart, a travelling platform or the like, and an obstacle such as a barrier, a buffer etc., or between two mobile machines.
More specifically, it relates to an impact absorbing device comprising an energy absorbing structure deployed by means of actuators set in operation by suitable control means, following detection of an impending impact, and prior to this impact.
Many systems for absorbing impacts and diminishing the effects of collisions by absorbing energy have been developed in the fields of railway transport, automobiles, shipping, aeronautics, and in general, for any industrial application wherein a structure may be subject to a risk of impact.
Impact absorbing devices developed to date can be classified into two groups.
A first group includes all impact absorbing devices comprising a deployable structure. These devices are, in general, characterized by low energy absorption level and slow deployment speeds, which make them unsuitable for certain applications. This deployable structure may take the form of an inflatable bag, as described in patent publication EP-A-0,816,178. In this case, however, the energy absorption level is low. Where this deployable structure is applied to an automotive vehicle, it can take the form of a structure located between the fender and the chassis of the vehicle, as described in the international application WO-A-92/18355. In this case, such systems are characterized by the complexity thereof. Furthermore, they only increase the amount of energy absorbed very slightly, and only over a very short travel, and are very heavy. Another example of this type of arrangement is disclosed in U.S. Pat. No. 5,810,427 to Hartmann, which does not disclose a means for detecting an impending impact, but rather a motor vehicle with a control unit that deploys an impact protection unit at all times while the vehicle is in motion. The control unit in Hartmann only evaluates whether the vehicle is in motion, it does not detect an impending impact. Also, Hartmann does not disclose a locking means for any or all of the parts of the deployed structure, and in fact, because Hartmann can be retracted after being deployed there can be no locking of the structure. Hartmann is also a slow deploying device, due to its spindle drive driven by an electric motor. Also Hartmann does not use a translational movement of any of its stays or scissor mechanisms, this means the overall structure cannot extend as far as it could if translational movement was provided. Lastly, another deployable structure used in safety barriers, particularly in the field of railways, is described in the document EP-A-0,724,999. In this document, the design of the structure is such that the deployment thereof is slow, and collisions may result in rebound phenomena, which can have serious consequences. In practice, this structure is deployed and collapsed by means of the scissoring movement of rigid beams. Energy is stored at the joints by torsion springs. This approach does not allow for the design of a rapid deployment structure (faster than 1 m/s), even if other propulsion means are used and the structure is made as light as possible. Furthermore, this approach does not allow for the design of a means of absorbing energy from high-speed collisions, as it results in the rotational movement of rigid members (before energy is stored, at high speeds of 10 m/s, the strength of the structure is highly dependant on speed).
The second group of impact absorbing devices comprises devices having fixed or stationary energy absorbing structures. This is the case for the impact absorbing device described in patent FR-A-2,712,950. The same is true of the structure described in patent FR-A-2/747/633. These devices are, in general, characterized by their particularly large dimensions. On the other hand, the arrangement of the absorbent elements of these devices allows for a considerable structural collapse travel, but this is still not sufficient to avoid damaging deceleration in the event of high-speed impact. Furthermore, these absorbent elements are incorporated at the level of the chassis and frame design of specific vehicles and do not, therefore, allow for improvements in the resistance to collisions of existing vehicles. Consequently, for this limited absorption capacity, each new design requires a specific study, and verification tests, which are expensive.
The object of the present invention is, therefore, to provide an impact absorbing device wherein the structural design allows for a high structural-collapse-length/initial-structure-length ratio, so that this structure offers a considerable collapse length, despite the small dimensions thereof, allowing for a non-critical deceleration travel.
Another object of the present invention is that of providing an impact absorbing device wherein the energy absorbing structure offers a high level of energy absorption, is rapidly deployable, and can easily be modified according to impact conditions.
Another object of the present invention is that of providing an impact absorbing device wherein the resistance of the structure during collapse thereof is controlled so that the structure can provide an absorption function at highly precise decelerations, and over a very wide range of collapse speeds.
For this purpose, an object of the invention is a device for absorbing impacts, in particular between a mobile machine, such as an automotive vehicle, a boat, a cart, an elevator, a train, an airplane, a travelling platform, etc. and an obstacle, such as a barrier, a buffer, etc. or between two mobile machines, or two parts of a single machine which may collide when the machine is subjected to impact, this device, which is constructed so as to be mounted on the obstacle and/or on the mobile machine, comprising an energy absorbing structure deployed by means of actuators set in operation by suitable control means, following detection of an impending impact, and prior to this impact, characterized in that the deployable energy absorbing structure comprises at least compressible beams which, when the structure is in the deployed position, absorb the energy produced by the impact, which is produced in a given direction, principally by the permanent axial compression thereof, wherein these compressible beams are connected to each other and/or to rigid guide elements by joints which allow for rotational and/or translational movement of these beams during the deployment of the structure, wherein these joints can be locked in the deployed position of the structure.
As a result of the design of the energy absorbing structure, despite the small dimensions of the structure in the initial position thereof, before an impact, the structure""s extension travel and its collapse travel are large, thereby avoiding any critical deceleration of a mobile machine.
According to a preferred embodiment of the invention, the rigid guide elements take the form of elongate bodies, such as beams, and extend in a plane substantially perpendicular to the direction of the impact.
As a result of the presence of these rigid guide elements, deployment is achieved in a perfect and reliable manner, and any dislocation of the structure at the moment of impact is prevented, even at high collision speeds and at very high energy levels.